Quick Answer
An inline shower filter screws between your shower arm and your current showerhead, so you keep the showerhead you like. A filtered showerhead replaces the whole showerhead and has filtration built in. Inline is more flexible and usually cheaper; filtered showerheads are more compact and all-in-one.
Problem
Buyers are unsure whether to add a filter inline or buy a new filtered showerhead. The wrong choice can mean a showerhead you do not want or a filter that does not fit.
Product Recommendation
ZOOSHEN offers both inline filters (keep your showerhead) and filtered showerheads (all-in-one). Replacement cartridges are available for both lines.